Vehicles can include an internal combustion engine that generates drive torque to drive wheels. More specifically, the engine draws in air and mixes the air with fuel to form combustion mixtures. The combustion mixtures are compressed within cylinders and are combusted to drive pistons that are slidably disposed within respective cylinders. The pistons rotatably drive a crankshaft to transfer drive torque to a driveline and ultimately to the wheels.
When the engine misfires, the combustion mixture of a particular cylinder combusts at an undesired time. More specifically, the temperature and pressure of the unburned air/fuel mixture within the cylinder exceeds a critical level and causes the gases to auto ignite. This results in engine knock and produces a shock wave that generates a rapid increase in cylinder pressure. Damage to pistons, rings and exhaust valves can occur if sustained heavy knock occurs. Additionally, engine knock causes undesired vibration and driveline oscillations.
Engine control systems may include misfire detection systems and/or knock detection systems to determine when the engine misfires. In this manner, the engine control system can regulate engine operation to inhibit engine misfire and improve engine performance and vehicle drivability.
Traditional knock detection systems include a knock sensor and a dedicated knock detection chip or application specific integrated circuit (ASIC) to process the knock sensor signal and calculate the engine knock intensity. An individual knock sensor and knock ASIC can be used to detect knock from each cylinder. The knock ASIC usually includes amplifiers, filters, rectifiers, integrators, A/D converters, sample and hold circuits and/or other analog circuits. This hardware is expensive, difficult to upgrade and calibrate and varies from manufacturer to manufacturer.